Can't Hold Back Any Longer
by polarbearz
Summary: The epitome of the Derek/Casey relationship from the way I see it, anyway. Inspired by the song "The Only Thing That Matters" by Spitalfield. Oneshot. Oh, and I don't own these characters or this show, or this song.


_Soft trace of your fingertips_  
_The round shape of your pressed lips_  
_Why can't this be easier for me?_  
_Why don't you_  
_Why don't you step a little closer, closer?_  
_And we'll show you how to make your heartbeat_  
_Why don't you dance a little closer, closer?_  
_And I'll spin you around_  
_Your heels will never touch the ground_  
_I thought we went through this_  
_I know that I can't be, the only thing that matters (whoa)_  
_I'll never settle down, settle down (whoa), unless it is for you_  
_Unless it is for you_  
_Unless it is for you_  
_And I wonder_  
_What you're doing while I wonder what you're doing now_  
_I can't turn around_  
_Why don't you step a little closer, closer?_  
_And we'll show you how to make your heartbeat_  
_Why don't you dance a little closer, closer?_  
_And I'll spin you around_  
_Your heels will never touch the ground_  
_I thought we went through this_  
_I know that I can't be, the only thing that matters (whoa)_  
_I'll never settle down, settle down (whoa), unless it is for you_  
_Unless it is for you_  
_Unless it is for you_  
_Into your eyes I've fallen even farther_  
_I don't think I can hold back any longer_  
_Into your eyes I've fallen even farther_  
_The only thing that matters now_  
_The only thing that matters now_  
_The only thing that matters now is this could be perfect_  
- "The Only Thing That Matters" / Spitalfield

Derek sat on the couch flipping through all the meaningless late night soap operas, music videos, and low rate sitcoms. It was one in the morning but he found it hard to sleep. He hadn't felt like going out that night either. Exams, teachers, parents… all of the above were just way to far up his ass this week for him to party on a Friday night. Sometimes it was easier to just relax. He wished that Casey was with him, providing warmth on the lengthy couch. They could curl up on the worn sofa instead of him sitting in the luscious black recliner. They could fight and flirt and maybe even…

No. He stopped himself before his mind got too far ahead of him. Derek bit his lip.

He pinched his muscular arm. He pulled his hair.

Anything to rid his school addled mind of the delicious images of Casey's lush pink lips pressed against his.

Too late.

What was wrong with him? A short time ago, he hated the girl. She was his parallel. Everything he avoided when choosing his mate of the week. Except she was just so…

_So what?_ Derek thought.

What was it that made that girl so irresistible?

She was just… so… vulnerable.

The way he could pick on her, tease, and taunt her. She could whine and whine, but it always seemed to make Derek even more excited about her torture.

And just when he thought he had her in his clutches, she was stubborn and tough.

That's what he liked about Casey. She was wild and inconsistent. At least, to her own merit. Really, she followed all rules, but in the sense of Derek's teasing, her reactions varied constantly.

The clock on the side table near the door glowed a large '1:10' and Derek groaned in frustration. He was hard. He wanted to tease Casey. And he was over tired.

As he turned to go upstairs, the door opened slowly.

Casey.

She was still the little innocent girl. Home before the 1:30 curfew, wearing a modest shirt and a mid-thigh black skirt. As Derek turned around below the stairs, his eyes flickered over Casey's body. Her clothes may have covered bare skin, but her shirt held her taught frame and showed off her round C cups in a way that didn't make her look like she was trying to parade her body around. It just looked natural.

Derek's jeans got the slightest bit tighter.

"Derek, what ever scheme you plan on pulling, can it wait until the morning? I really can't deal with you right now," Casey hissed, glowering. She couldn't stand her step-brother. Especially not this late at night. Or was it early in the morning?

He only stared for a moment before catching himself and shaking his head.

"There's no scheme, Case. I, uh…"

His mind had completely escaped him, for there was nothing more to say. Casey just yawned and undid one or two buttons on her shirt. This, in turn, only made Derek's body more reactive. However, he quickly turned to his usual persona.

"Jeez, a striptease, Case? I thought a mature, sensible girl like you would know better. But since you don't…" He paused, grabbing his wallet off the table and handing her a dollar. "Here."

Casey flushed and scowled, angrily placing her smooth palms on Derek's chest and attempting to shove him. (No avail of course.)  
"You're sick, Derek. You know that?"  
"So I've been told," he snarkily replied, noticing briefly that her hands were still on his sculpted chest. They were warm even through the cloth of his t-shirt.

With his insides quivering, Derek met her eyes only briefly, before leaning in.

"If you'd kindly remove your perfect little hands, I'd like to get some sleep now," he whispered with just the proper amount of emphasis on _perfect_.

Casey, who wasn't used to his warm breath on the shell of her ear, felt her own breath hitch at his words. Instinctively, she stepped closer to him, meeting his eyes boldly. It was like she couldn't explain it, like she was captivated by his gaze. After an eternity, her hands fell from him, and Derek swiftly made a move toward the staircase.  
Derek himself could feel his heart pounding in his chest. He had almost kissed her- Casey, his wicked step-sister who hated him more than anything. What had happened back there?  
At the bottom of the stairs, Casey watched his retreating figure and began to unbutton her shirt completely, following him. Not to his room of course, but they both lived upstairs, so this was only natural.

Derek heard her following him, and turned around to say something. He hadn't wanted to look back at her, he had been afraid to, but his obsession with Casey had lead him to do so. Now he was thankful, so, so thankful he had. There, in all of their glory, were Casey's perky breasts, nestled in a pink cotton bra with white lace detail. This was the type of bra Casey would wear, Derek couldn't help but think.

"Derek!" She hissed, bounding up the stairs and reaching him. "You did not just see that!"  
He snickered and gave a small nod in reply, immensely hoping she could not see how impossibly tight his jeans were.  
She reached out, smacking him lightly and growling in frustration.

"You are such an impossible skeeze!" She whined, glaring at him.

He just chuckled and stood there on the landing, eyes falling to her full lips and wondering how they would feel on his, or on his neck, or on his cock…

"You did it on purpose, Case," he finally murmured, feeling way too horny to stand here and have this argument.

Growling once more, Casey reached to shove him again. However, Derek caught her hands and held her still. He paused, musing over his options from here. Then he leaned in, emboldened with overtiredness.

"Kiss me, Casey," he commended in a gruff whisper, knowing for a fact that every other girl he'd ever kissed had fallen for this.  
"Are you drunk?" Casey cried, eyes wide, feet glued to the ground. She couldn't move, she couldn't breathe. Her girlish fantasies were about to come true. As much as she liked to pretend she hated Derek with all of her heart, Casey couldn't deny her attraction to his douchey attitude. That was what bothered her most- his personality. It made her hate him, when all she really wanted to do was…  
"Kiss me," he repeated seriously, pulling her a tiny bit closer.

Unable to stop herself, Casey felt her body sway towards Derek's, their lips meeting in a manner she could only describe as heavenly.  
After the count of three, Derek pulled back slowly, knowing it would keep her wanting more.  
"Derek," she whisper whined, licking her lips.

He grinned and picked her up, spinning her around and carrying her to his room. Casey nearly protested, but instead she forced their lips to connect again, silencing her mind.  
From there, it was a blur of Derek undressing himself and producing a condom while Casey laid on his bed and admired his body dizzily.

"What about George and Nora?" She inquired, too weak with lust to move.

"You're the only thing that matters now, Case," Derek answered, secretly knowing that he was telling the truth. It had always been the truth, ever since she'd come into his life.

He crawled onto the bed, kissing her passionately as he removed her skirt, and then her bra. Their tongues fought for dominance as he pushed her unbuttoned shirt away and worked her breasts. Casey groaned into Derek's mouth, arching her back and pleading for more. In response, Derek broke the kiss and sucked at her neck, chuckling against her sweet skin.  
Now she whined, squirming beneath his simple ministrations, but he didn't give in. Instead his mouth met her breasts, teeth grinding against her nipples while his hands still massaged. Casey's hands tangled themselves within his hair, and she gasped as he began to kiss down…

Derek's hands hurried down first, however, quickly removing her underwear. His tongue soon followed, innocently meeting her wetness, poking and prodding mercilessly. Casey hissed and opened her legs wider, demanding that Derek enter her in the form of a strangled whispered plea.

His tongue dove in, tasting her, and tracing her walls before he found her clit. He gave it two swift licks and then removed himself completely from her body.

Then he flopped back on the bed and smirked at Casey, finding a way to tease her despite the fact that he needed her so terribly. He knew it would drive her crazy, and that was Derek's favorite thing to do, even when they were about to have sex. Besides, he knew she'd like the challenge, even if she'd never admit it.

Casey could not believe Derek was doing this to her. Somehow that boy always had the upper hand in everything they did, and now was no exception. Unable to do much else, she jumped at the chance and threw herself on Derek's erect penis, riding him as hard as she could, moaning unstoppably. Derek groaned as well, thrusting each time she came down to meet his pelvis. It didn't take long for Casey to cry out as she came, and Derek sat up to silence her with a kiss, which only forced him deeper into her. Rocking against her three times, Derek was able to orgasm as well.

It was 3 am now, and Derek crawled back into his bed after throwing out the condom, kissing Casey once again. She pulled away though, looking up at him seriously.  
"Do you think maybe, you could, be mine? Only mine?" She murmured, hating the way she sounded, like some stupid romantic novel heroine. But that was how she felt, and now she wanted Derek to just be with one girl, her. She didn't want to walk into the locker room for gym class monday morning and hear random girls talking about how good Derek was in bed on saturday night. She just wanted him to be hers. That was the only thing that mattered.

He snickered and kissed her again. "This could be perfect," he answered in her ear, his breath hitching as her hand started to slide beneath the blanket in response.


End file.
